[ntp:questions] Stability problem on PowerEdge (SuSE 9.3)

Richard B. gilbert rgilbert88 at comcast.net
Sat Feb 24 17:43:24 UTC 2007


Till Wimmer wrote:
> Hi there,
> 
> i try to settle some time accuracy in our office environment...
> 
> Our main server is running SuSE 9.3 on AMD64. I installed the xntp 
> package from SuSE (Vers. 4.2.0a-35).
> Hardware: DELL Power Edge 2850
> 
> uanme -a:
>  Linux office 2.6.11.4-21.15-smp #1 SMP Tue Nov 28 13:39:58 UTC 2006 
> x86_64 x86_64 x86_64 GNU/Linux
> 
> /etc/ntp.conf:
> --- snip ---
>  driftfile /var/lib/ntp/drift/ntp.drift
> 
>  server 127.127.1.0
>  fudge 127.127.1.0 stratum 13
> 
>  server 0.debian.pool.ntp.org iburst
>  server 1.debian.pool.ntp.org iburst
>  server 2.debian.pool.ntp.org iburst
>  server 3.debian.pool.ntp.org iburst
> 
>  disable auth
> --- snap ---
> 
> Short after starting, everythings looks ok:
>      remote           refid      st t when poll reach   delay   offset  
> jitter
> ============================================================================== 
> 
> *typhoon.aput.ne 192.12.19.20     2 u  227  256  377  170.905  -14.600   
> 5.776
> +bitvalve.org    192.53.103.108   2 u  166  256  377   32.163  -15.190   
> 4.488
> +8.15.10.42      132.163.4.103    2 u  170  256  377  105.118  -11.706   
> 3.857
> -ns.oredin.net   193.190.230.66   2 u  179  256  277  141.835   36.960  
> 17.438
>  LOCAL(0)        LOCAL(0)        13 l   49   64  377    0.000    0.000   
> 0.001
> 
> But after 3..5 hours all peers are rejected (ntpq> as) and LOCAL(0) is 
> the sync source.
> 
> I checked the firewall, disabled all restrict settings, disabled chroot 
> and running as unprivileged user, a.s.o.
> 
> Now i found that pps stability is always 512ppm and pll has a huge offset.
> 
> ntpdc> kern:
>  pll offset:           4294.95 s
>  pll frequency:        22.694 ppm
>  maximum error:        0.364061 s
>  estimated error:      0.017754 s
>  status:               0001  pll
>  pll time constant:    4
>  precision:            1e-06 s
>  frequency tolerance:  512 ppm
>  pps frequency:        0.000 ppm
>  pps stability:        512.000 ppm
>  pps jitter:           0.0002 s
>  calibration interval: 4 s
>  calibration cycles:   0
>  jitter exceeded:      0
>  stability exceeded:   0
>  calibration errors:   0
> 
> I set the hwclock -w and started fro scratch, but short after the offset 
> was the same.
> I can't believe that the clock of this server is this terribly 
> inaccurate... IMHO it's "professional" hardware. At least it was 
> expensive ;)
> 
> Any help would be very much appreciated!
> Till
> 

Three of your servers have round trip delays that are extreme by most 
standards.  Try to find servers closer to you.  I don't use pool servers 
myself but I believe that you can select regional servers by; e.g.
us.pool.ntp.org for servers in the United states
eu.pool.ntp.org for servers in Europe
etc.

Twenty milliseconds round trip delay is a good number.  Make every 
effort to stay below thirty milliseconds.





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